This invention relates generally to the removal of material from an isolated environment such as an isolation chamber for transport, storage, or disposal. More particularly, the invention relates to a method and apparatus for effecting a transfer of material from an isolation chamber while maintaining at all times the integrity of the isolation chamber, maintaining isolation of the transfer container, and leaving no residual material, such as contaminants, on the sealing surfaces of the chamber and/or container.
Many research and industrial processes involve the use of environmentally undesirable or toxic materials. Examples of such materials are toxic materials used in or produced by chemical, biological, or nuclear research or production methods. These processes, and the materials used therein, are isolated from the ambient environment through the use of containment or isolation chambers such as gloveboxes and negative-pressure hoods, forming isolation chambers.
The undesirable or toxic materials used or produced in these isolation chambers must be safely removed from the environments for transportation and further processing or disposal. The nature of the materials requires that the integrity of the isolation be maintained at all times, with respect to both the chamber and to the container used to transfer the materials. It is also necessary to ensure that no undesirable material residues be left on any surfaces external to the isolation chamber or the transfer container.
One current method of transferring the material is to place a container or xe2x80x9cbagxe2x80x9d into the isolation chamber. The materials are placed into the container which is sealed and then removed from the isolation chamber through what are known in the art as xe2x80x9cbag-out ports.xe2x80x9d The use of bag-out ports creates special problems. The ports must be made so as to permit the introduction and removal of the containers, but must simultaneously maintain the integrity of the isolation chamber. Between transfers, the bag-out ports must be capable of being sealed or forming a seal so the isolated environment can be used, again without breaching the integrity thereof. The apparatus associated with, and the processes of, using bag-out ports make it difficult to handle large or irregularly shaped items and make it difficult to keep external surfaces free of contamination.
A highly specialized bagless transfer system for use with certain relatively high-level nuclear materials is disclosed in U.S. Pat. No. 5,740,545, issued Apr. 14, 1998, and assigned to Westinghouse Savannah River Company. The disclosed apparatus and process are specific to the particularly designed metal containers into which the material is transferred from a glovebox and to the handling apparatus for the containers.
The referenced patent discloses a handling apparatus which manipulates the metal container and inserts it through a seal in the glovebox. Radioactive material in the glovebox is placed into the container. A specifically designed hollow metal plug, manufactured to possess very close physical and dimensional tolerances, is placed within the container at a predetermined location therein. A rotary welder, such as a TIG welder, is used to form a weld between the plug and the container, after which a defined cutting means severs the weld.
Because the plug is hollow, the severing results in a portion of the container remaining in the glovebox seal, the portion closed off by the plug half in that portion. The other plug half forms a seal for the metal container itself, which may then be transported for disposal.
While the apparatus and method of the referenced patent have been used with the radioactive materials, it is of little or no practical use with other materials and other types, sizes, or shapes of containers. The disclosure of the referenced patent requires the use of special materials and extraordinarily precise manufacturing tolerances to form the metal container and metal plug. Likewise, relatively complicated manipulation means are required to perform the metal welding and sever the weld. For example, the patent requires the use of a rotary welder tip and a set of circular cutting blades. Each of these devices must be precisely positioned and manipulated. Likewise, the shape and size of the container itself are necessarily limited.
There is therefore a need for a process and apparatus to effect a bagless transfer of material, the process and apparatus being adaptable for use with a wide variety of materials and containers, and capable of use with substances other than metal.
It is an object of this invention to provide a novel and widely practicable apparatus and process for effecting the clean, contamination-free transfer of materials from an isolation chamber.
It is also an object of this invention to provide a contamination transfer system capable of use with containers of varying shapes and sizes.
It is likewise an object of this invention to provide a cost effective bagless transfer system suitable for use with different kinds of environmentally undesirable or toxic materials.
It is furthermore an object of this invention to provide cost-effective and relatively uncomplicated processes and apparatus for effecting bagless transfer.
These and other objects of the invention are provided by a method for effecting bagless transfer of material from an isolation chamber into a storage carrier, the method comprising the steps of communicating between said isolation chamber and said storage carrier through a conduit, said storage carrier being in hermetic relationship with said conduit and having an interior therein in communication with said isolation chamber through said conduit; transferring said material through said conduit into said interior of said storage carrier; inserting a plug into said conduit, said plug having an upper surface, a lower surface and a circumferential wall connecting said upper surface and said lower surface; radially sealing said circumferential wall to said conduit to divide said conduit into a sealed first portion communicating with said storage carrier containing said material and a second portion hermetically isolated from said sealed first portion and in communication with said isolation chamber; and severing said conduit and said plug at a point between said upper surface and said lower surface of said plug to remove said sealed first portion of said storage carrier from said second portion to permit relocation of said material within said storage carrier. Apparatus capable of being used in the process is also provided.